Low voltage transformer loading example

The majority of exterior waterproof low voltage transformers are wire wound ( magnetic)
torodial which are sealed in hard resin to prevent water ingress. The transformer
must be loaded to 70% of it maximum capacity for it to function correctly. If you
are going to put LED lamps on the transformer we recommend loading it to 80% of its
maximum load capacity.

Transformer location and low voltage cabling

1. Try and keep cable runs from transformers to garden light
fittings as short as possible to ensure optimum performance, no
more than two metres to the first
lamp.

2. Locate a transformer centrally amongst a group of garden
lights it is to power; e.g. a radius of 8 metres for 50w lamps

3. If you decide to run 2 sets of garden lights operated
by separate switches, you must provide 2 separate transformers & circuits.

4. Try not to put more than 12 lights on any one transformer
otherwise voltage drop can reduce lamp and transformer performance.

5. Try to avoid putting cable runs straight through the
middle of the garden and try to run them along the fence line first, this will
reduce the risk of putting a spade or
fork through them when gardening.

6. Where possible always try to keep the transformer above
ground mounted on a fence post or spike, if you do have to bury them
make sure you use the burial kits
and fill with resin to reduce water ingress.

InstallationMake
all connections in T9969 underground joint kit or similar resin-sealed
joint. (Boxes with silicon-sealed lids do not protect against ingress of
moisture through condensation and capillary action: ordinary silicon
sealant does not bond reliably with all enclosure materials.) After
burying the transformer and associated junction boxes, lay a paving slab
or similar protective material over it, cover with cable warning tape
and back-fill hole. NB: Where multiple ground burial transformers are to
be installed in an area, allow connection points where possible above
ground to allow for isolation in the event of future fault-finding.
Connection of transformers to separate cores of a multicore cable may
also be considered. Failure to adopt these recommendations may mean
difficulty in fault diagnosis in the future and in extending or
upgrading the system.